Python: fix empty string output formatting

[TomBinford]

Running this Python code

print('a')
print('', end='')
print('b')

output: expected output: This is the cause. As far as I can tell received will always be true, when it should be false if text === ''. https://github.com/uclaacm/TeachLAFrontend/blob/b4132fb4d472b650a71435d7c14c8b00d133e6f8/src/util/languages/Python.js#L6-L16